The tools don't work this way. The ratsnest is not dynamic. It will only update once you place the part down. You could assign a FUNCKEY to place the part down and pick it back up again which will update the ratsnest connections. Edit your env file to include

Is there an option setting for making the ratsnest 100% straight all the time? I am seeing often that some of the rats zig-zag off the origin and destination pin and this can sometimes be visually confusing.

The ratsnest in Allegro is not dynamic. The older Layout product had a dynamic ratsnest, cadence are a bit behind in this respect.

There are settings that can help a little.

Click Setup > Design Parameters on the tool bar. In the dialog box set the ratsnest geometry to Straight. You can also set the ratsnest points to either closest endpoint or pin to pin. Closest enpoint works pretty good.

Other things you can do to make life easier is assign colors to specific nets like ground and power, Disable a ratsnest from showing, Blank all ratsnests so when you move a part only those nets show up.

Make sure they are turned on (Display - Show Rats - All) then invoke the command Edit - Move and make sure that Stretch Etch is not checked (Options fold out menu on the right hand side). If it is the rats become invisible when moving a part.

I am struggling with the rat lines as well but in my situation the "Closest endpoint" setting is not functioning properly. I opened a case over 17 months ago and I was told this is the way the tool is designed to work.

For instance when I finish a route and exit the command I see the rat line extend across the design to a pin to my plating bar when I have a via 100 microns in front of the end point of the route. I just opened another case since this is a later release and I am told the tool functions as designed and nobody else has asked for an enhancement.

I remember back in the day when User Groups were strong and the users would all have a presence to openly discuss issues with the tools in front of the developers. I miss those days because other vendors were responsive to those open forums.

There are many tools on the market both cheaper and more expensive that have the ability to show the rat lines from a route to any of the closest end point (i.e. via, pin, bond finger, etc.) that provide the designer a very helpful guide to plan accordingly at a glance where to route and how to get there in the path of least resistance. I do not have that using this tool and feel like I am not being heard that this is indeed a problem.